This invention pertains to a novel synergistic herbicidal composition which has been found particularly effective in controlling the weed wild proso millet (Panicum milaceum).
Wild proso millet is a rapidly spreading grass weed which is difficult to control. It is particularly prevalent in corn and other crops and is found primarily in the upper mid-western states of the United States such as Wisconsin, Minnesota, Iowa, Nebraska and Michigan, adjacent parts of Canada such as Manitoba and Ontario provinces, and in certain portions of Europe, including France, Italy, Austria and the U.S.S.R. This weed has a long germination period, which may be 2-3 months. Many pre-emergent or pre-plant incorporated herbicides utilized in controlling weeds in such crops have an effective activity of less than three months, sometimes by design--to permit quicker biodegradability and less residue in the soil. Consequently, such herbicides may not provide effective control of this weed.
Currently only two registered treatments in the United States provide adequate control of this weed in corn crops. One is a pre-plant incorporated application of the herbicide Eradicane.RTM. (ethyl N,N-di-n-propyl thiocarbamate or EPTC plus the herbicidal antidote N,N-diallyl-2,2-dichloroacetamide) followed by a post-emergence directed application of the herbicide ametryne [2-(ethylamino)-4-isopropyl-amino-6-methylthio-s-triazine]. The other registered treatment is a pre-plant incorporated application of Eradicane.RTM. followed by an early post-emergence application of the combination of pendimethalin [N-(1'-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzeneamine] together with cyanazine [2-chloro-4-(ethylamino)-6-(2-cyanoisopropylamino)-s-triazine]. In either of these applications, Eradicane.RTM. Extra (which comprises the Eradicane.RTM. formulation plus a herbicide extender) may be substituted for Eradicane.RTM.. The first of these two treatments poses a serious risk of corn injury from ametryne and requires sophisticated equipment; this method therefore is not popular. The second method is expensive and presents a substantial risk of pendimethalin injury to the corn. Furthermore, the latter method does not suppress the production of new weed seeds which contribute to the infestation in subsequent years.